The invention relates to liquid crystal displays and, more particularly, to a liquid crystal display for a hand-held apparatus that is adapted for use in different orientations.
The explosion in the use of hand-held electronic devices, such as organizers, pagers and cellular telephones including liquid crystal displays (LCDs) to provide text and/or graphical output to the user, has been dramatic in recent years. LCDs are desirable because of their small size and weight and low power requirements which makes them ideal for use with hand-held electronic devices. LCDs are also capable of displaying different types of images, such as characters, graphics, captured images, such as photographs, or the like. Many LCDs are reflective, meaning that they use only ambient light to illuminate the display. Others require an external light source such as a back lit computer display screen.
LCDs do have drawbacks, such as with respect to their viewing angle. The viewing angle of an LCD defines the field of view in which a user can see characters or images displayed by the LCD, relative to the display surface of the LCD. With conventional LCDs, the viewing angle is limited, and thus, characters or images on these LCDs are not visible from all possible views. Moreover, items displayed on LCDs normally exhibit asymmetrical visibility, which means that the visibility of a character or image depends not only on the angle at which the LCD is viewed, but also depends on the direction at which the LCD is viewed. The viewing angle and contrast setting of an LCD are closely related and both are controlled by a drive voltage applied to the LCD. As the applied drive voltage changes, so does the viewing angle of the LCD. Each different LCD viewing angle is associated with a different viewing angle cone for the user so that depending on the relative position of the user and LCD, there is a particular voltage that produces an optimum LCD viewing angle for providing a viewing angle cone for the user that maximizes the visibility of the characters on the screen.
Typically, a user adjustment is provided such as by a knob that controls a potentiometer or variable resistor of a contrast adjustment circuit for the LCD. Accordingly, manual operation of the control knob adjusts the drive voltage applied to the LCD for adjusting the viewing angle thereof. Other types of user/operator interfaces also are known such as with control keys for operating Windows or icon based software programs that allow for a contrast adjustment mode to be selected. In the contrast adjustment mode, different contrast settings can be selected according to user preferences. In this manner, different levels of drive voltage and thus viewing angles can be keyed into the device for changing the viewing angle of the LCD under microprocessor control. However, where the device is consistently disposed in orientations that are different but predictable relative to the user, it is undesirable to have to continually adjust the contrast setting to obtain the appropriate viewing angle for the LCD. This occurs with hand-held electronic devices that are used by both right and left-handed people, for instance.
For example, clip-on type organizers are known that can be attached to the back of a cellular telephone so that the information stored in the organizer can be shared with and/or used by the phone such as for allowing one-touch calling of a number stored in the organizer. Where the keys are asymmetrically arranged on the organizer, i.e., on one side or the other of the LCD, the user can be at a disadvantage depending on which hand they tend to hold the phone with. For instance, where the keys are arranged on the right-hand side of the LCD for use by right-handed users with the phone held in the left hand and generally facing downwardly so that the organizer LCD can be viewed, the characters are in their standard, upright readable position on the screen. However, with a left-handed user who tends to hold the phone in their right hand to keep their left hand free for punching the keys on the phone and organizer, when they turn the phone so that it faces downwardly for viewing the LCD of the organizer clipped onto the back of the phone, the keys will now be on the left hand side of the LCD with the characters appearing inverted from their standard, upright readable position. To accommodate both right and left-handed users, the orientation of the characters can be shifted or rotated 180xc2x0 so that when the left-handed user views the LCD, the characters will appear in their standard, upright readable position thereon.
It is also true that the organizer LCD screen will generally be at a different orientation relative to the user depending on whether they hold the organizer in their right or left hand with the keys accessible to their free strong hand. At different orientations, the visibility of the LCD display can vary greatly because the orientations can entail different viewing angles and different viewing directions. This can be a serious problem where both right and left-handed people use the same phone and organizer, or where the phone and organizer are regularly held in either hand, during operation or when the organizer is detached due to the configuration of the phone antenna or flipped-open portion of the phone. Thus, each time a user holds the phone with the hand opposite to the one previously used, employed or where a single user uses different hands for holding the organizer alone versus when it is clipped to the phone, an adjustment will have to be made to the contrast setting and viewing angle to accommodate for the different orientations of the screen.
Accordingly, there is a need for a hand-held electronic device that allows it to be used when held in either the right or left hand of a user while keeping the visibility of the images on the LCD maximized. More particularly, a hand-held electronic device that includes keys asymmetrically arranged relative to an LCD screen thereon, and where the characters on the screen can be shifted and rotated so that they can be read in their upright position by both right and left-handed users of the device, is needed where the viewing angle of the LCD is automatically adjusted to accommodate both right and left-handed users without requiring manual adjustments to the contrast setting.